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Friday, 14 April 2017

Les Ponts Neufs renewed

I'm quite a fan of Breton architect Louis Auguste Harel de La Noë, leading architect of the (now closed) Cotes du Nord railways. Born in Saint Brieuc, de la Noë studied in Paris
before returning to Brittany as chief engineer of roads and bridges for
the Côtes du Nord in 1901. He had already won awards for an x-shaped
bridge in Le Mans (sadly destroyed in the Second World War) and for his
pioneering work in reinforced concrete construction. He would now play a
vital role in the building of the region's new local rail network, impressing
with his light and elegant bridges.

The x-shaped bridge, Le Mans

For tourists, the railway was a way of accessing the beautiful
Breton coast. For those who lived in the region, it was an essential way
of moving around an area whose infrastructure was otherwise poor.
However, the line faced growing financial losses and closed in 1948. Since then, other bridges have been demolished; thankfully, this one has been spared that fate.

Over 237 metres long and 27.6 metres high, the Ponts-Neufs viaduct is an
impressive sight. The tall pillars and ornamented spans are more than
visually appealing, though: constraints of time and budget called for technical innovations. Built in 1913, this was among the first reinforced concrete
constructions. Building methods including prefabrication and
standardised processes were also novel.

The joy of Harel de la Noë's work is that it is attractive and
distinctive, going beyond the purely functional. Unfortunately, the pioneering nature of the technology he used brought its own
problems. The sand used included salt; bubbles were not removed by
vibration; and the steel was insufficiently protected.

The viaduct during construction

Nonetheless, the
bridge not only survived but continued to soar over its valley - and thanks to the hard work of the association devoted to promoting and preserving his work, it has recently been restored and brought back into use for pedestrians and cyclists.

3 comments:

There's an X-shaped crossing on the London Underground to the west of Gloucester Road station. Although controlled to a nicety by signalling, it causes constant delays. But of course, since the Underground was built just below the surface, crossing one line above another, as was done later on the deep Tube, was not an option.

I believe that Harel de la Noe regarded concrete as a temporary material and expected his bridges and viaducts to be replaced by the march of progress in due course. Attempts to repair and conserve them are therefore particularly ironic....